Recent Progress in Cobalt-Based Electrocatalysts for Efficient Electrochemical Nitrate Reduction Reaction

Electrochemical nitrate reduction reaction (NO3-RR) provides a sustainable and efficient way to producing ammonia at ambient condition and denitrifying wastewater. However, NO3-RR is still confronted with some barriers at present, because of the sluggish reaction kinetics and competitive hydrogen evolution reaction (HER). Particularly, it requires highly robust and selective electrocatalysts, which steers the complex multistep reactions toward NO3-RR process. Among the various electrocatalysts, Co-based electrocatalysts demonstrate a rapid reaction kinetics, steady catalytic performance, and suppressive impact on HER for NO3-RR, attracting more attention. In this review, it is focused on Cobalt-based electrocatalysts design for NO3-RR and the corresponding design strategies are summarized. In detail, these can be concisely classified into five categories, including the Co-based oxides and hydroxides, alloys, metal, and heteroatom-doped materials, metal organic frameworks and derivatives. Each category is extensively discussed, with its design concepts and ideas clearly conveyed through appropriate illustrations and figures. Finally, the scientific and technological challenges as well as promising constructing strategies for NO3-RR system in the future are discussed. It is expected that this review can provide valuable insights and guidance into rational design of Co-based electrocatalysts for NO3-RR, ultimately advancing their applications to industrial scenario with high current density, stability, and energy efficiency.